1. Field of the Invention
The present invention relates to a lockable gas spring arrangement.
2. Description of the Related Art
In the past (U.S. Pat. No. 4,807,855), gas springs included a closed cylinder with a cylinder interior which is filled with compressed gas and which is subdivided into a first and a second chamber by a displaceably guided piston, which on one side has a piston rod which on one front face of the cylinder is guided outwardly in a sealed manner out of the cylinder interior. The first and second chambers are connected together or are able to be connected together. The arrangement includes a fastening tube with a larger internal diameter than the external diameter of the cylinder and has a length which is smaller than or the same as the maximum extension length of the piston rod and which is fastened with its one end in the region of the free end of the piston rod and on which a locking element is arranged. The locking element is able to be moved substantially radially to the piston rod between an unlocked position permitting a free insertion movement and a locked position bearing against the front face of the cylinder on the piston rod side when the piston rod is extended. The locking element is able to be urged by a spring into its locked position.
In such a known gas spring arrangement, a locking pin is displaceably guided radially on the locking cylinder and loaded by a pretensioned spring towards the piston rod.
When the piston rod is extended, the locking pin moves until it comes to bear against the piston rod, whereas when the piston rod is retracted the locking pin is moved until it comes to bear against the cylinder.
Such a gas spring is used, for example, for opening flaps or doors, in particular on motor vehicles, utility vehicles or agricultural vehicles and machines, wherein the flaps and doors are pivoted upwards, in particular about a horizontal axis, from a substantially downwardly oriented position for opening into a substantially horizontal position.
Gas springs with a large extension stroke of the piston rod are frequently required here.
In order to hold the flaps or doors securely in the open position, and to avoid inadvertent pivoting-back, the locking pin comes to bear against the front face of the cylinder on the piston rod side and thus prevents the retraction of the piston rod. Only when the locking pin is pulled outwards manually counter to the force of the pretensioned spring in a radial manner, and thus moved out of the region of the front face of the cylinder, can the flap or door be moved in manually counter to the extension force of the gas spring in the cylinder.
In particular, with large flaps and doors, the extension force of the gas spring is high and requires both hands to grip the flap in order to be able to move said flap into its closed position.
This is, however, not possible in the known gas spring arrangement, as one hand is required for pulling the locking pin.
It is, therefore, an object of the invention to provide a lockable gas spring arrangement of the aforementioned type which permits a simple and comfortable operation for retracting the gas spring.